Process of neutralization



Aug. 8, 1933. CALDWELL PROCESS OF NEUTRALIZATION Filed April 25, 1930 1VENTO Ly/e 6a/gwe/i BY ,(f M

ATfORNEY Patented Aug. 8, 1933 rnocass or NEUTRALIZATION Lyle Caldwell,Long Beach,-alif., assignor, by mesne assignments, to California FirstNational Bank of Long Beach, Long Beach, Calif., a national bankingassociation, as trustee Application April 25. 1930. Serial No. 447,275

19 Claims. (01. 196-j-41) This invention relates to improvements in aprocess for refining oils wherein acid treated oils may have theiracidity neutralized.

The principal object of the invention is to provide a process ofneutralization wherein an acidtreated oil is contacted with an alkalinecompound of stable structure in the presence of water and capableofforming water soluble salts of the acid in the oil.

A further object of the invention is to contact a petroleum product,such as gasoline, pressure distillate, kerosene, lubricating oil or thelike, which has been treated with an acid, such as sulphuric acid,hydrochloric, and/or the like,

115 with an alkaline mineral whereby water soluble sulphates, chlorides,or the like are formed on the surface of the mineral and then removed bywashing the mineral with water.

In the. refining of oils, such as petroleum prodnets and animal orvegetable oils, it is customary,

in order to remove certain undesirable constituents, to subject the oilto a treatment with acid with agitation, whereby the undesiredconstituents combine with the acid and are removed therefrom in a formknown as "sludge, which sludge, being heavier than the oil, will settleby gravity and may be then removed from the oil. However, in such acidtreatments, the acid and acid reaction products become very finelydivided, to the end that, after the sludge is withdrawn from the oil,certain acid particles are so dispersed as to render the oil acid.Further even than this many of the acid products are soluble in thehydrocarbon oil. Such acid may best be determined by shaking a knownquantity of the oil in question with a known quantity of distilled wateror other suitable liquid which is immiscible with the oil. The water orother suitable acid solvent is then separated from the oil and itsacidity determined by suitable means. I prefer to express this acidityin terms of hydrogen ion concentration by means of the well known pHscale full details of which may be found in any standard reference worksuch as that of W. M. Clark, The Determination of Hydrogen Ions." As iswell known a pH of 7 represents neutrality, relative degrees of aciditybeing represented by unit figures smaller than '7 and relative degreesof alkalinity by unit figures larger than 7. In other words. a pH 01 4represents an acid condition, a pH of '7 represents neutrality and a pHof 9 represents a condition of alkalinity. The pH may be determinedelectrometrically or by indicators.

Therefore any neutralization effect should closely approach '1 on theabove scale to obtain the best results.

Ah ordinary alkaline neutralizer is a solution of caustic soda which,when added to acid treated oil after sludge withdrawal, is capable ofbringing the pH of the oil to approximately '7. After 7 the alkalinesludge is withdrawn, the oil must be washed with water and perhapsfiltered through clay.

However, the use of caustic soda or other alkaline solutions presentsdifiiculties which are now overcome by this-invention, in addition toperforming a desired neutralizing action, all of which can be done in asimple, quick, and highly economical fashion.

For instance, the use of caustic soda requires a procedure usually asfollows:

(1) Preliminary washing of acid stock with water.

(2) Washing with caustic soda solution.

(3) Washing with water.

A certain amount of emulsification occurs in each stage of thistreatment, and its separation, especially in continuous types ofequipment, is a difiicult problem. Frequently the amount of 30 moistureor caustic in suspension with the settled oil or distillate will run ashigh as one percent and this must be removed by evaporation or by otherequally difiicult methods. When there is such residual moisture in acaustic washed oil 35 and evaporation is resorted to, the salts andother impurities in the aqueous portion are deposited in the heatingequipment as sediment and frequently as a troublesome scale. In otherwords, my process eliminates the necessity of excess water andconsequently emulsions and the above mentioned difliculties are avoided.

Due to the fact that it is usually impossible to accurately estimate theexact amount .of acid to be neutralized, an excess of caustic isnormally employed to be certain that all this acid is removed from theoil. This necessitates large quantities of caustic and as an example, toeflectively neutralize a distillate of approximately 44 BQgravitycontaining 1000-1300 mg. per liter of mo acid as H2804 it requiresapproximately 0.5 lb. of caustic soda per bbl. of distillate. Based on aprice of 3 cents per lb. the material cost per bbl. of distillate wouldbe 1.5 cents. Using my process and employing either brucite or causticcalcined magnesite for example, the material cost would be approximately0.4 cents per bbl. for neutralizing this same distillate. g 4

This invention provides a desired neutralization and the elimination ofthe above described drawno Brucite MgO.HnO 6 to 6. 9 Magnesite M300; 4.3 Hydro magnesite MgCOL3H O 6. .5 Dead burned magnesite MgO 4. 6 Causticcalcined magnesite MgO 6. 5 Calamine HzZNzSiOs 4. 4 Rhodochrosite M110013. 9

In general, while members of the above list give fair results,conditions of operation are that the material shall be insoluble (in apractical manner) in water and form an acid reaction compound which isrelatively highly soluble in water.

Preferably brucite is most desirable for use in my process inasmuch asit is found in comparatively large bodies in nature, and has a strongphysical structure, especially in the presence of water, yields highlywater-soluble salts upon contact with acid and acid-reaction products,and then may have its surfaces easily washed free from reaction-productsto give fresh surfaces for further contacting. Brucite is a naturallyoccurring magnesium compound identified mineralogically as MgO.HzO andbeing identified chemically as magnesium hydroxide (Mg(OH)2). Themagnesium compounds generally are preferred, especially those of strongphysical structure in the presence of water which indicates a lowsolubility in the .water, or substantial insolubility therein.

It is further to be noted that when, for example, where brucite is used,the soluble salt formed, in this case magnesium sulfate, crystallizeswith 7 molecules of water of crystallization which is sufficient toremove from the system such traces of moisture as may be necessary toactivate the original raw material.

As an illustration of an application of the invention the accompanyingflow sheet and drawing show a mode of operation in which neutralizationof acid oil is effected and in which washing of the brucite isaccomplished for continuous operation.

A tank 10 contains an oil, such as a pressure distillate. which issupplied to an agitator 11 in which the oil is treated with say, tenpounds to the barrel of strong sulphuric acid supplied through pipe 12.

After a period of agitation, the sludge is permitted to settle and iswithdrawn through a pipe 13 and the oil having a residual acidity of1200 parts per million, more or less, may be passed through a filter 14of the type, for instance, shown in United States Patent 1.739.898, Gardet al.. or through other filter aids such as diatomaceous earth, clay,or the like, or by centrifuging. Such filtering is not necessary butwill reduce the acidity of the oil and thereby add to the efliciency ofthe neutralizing step.

The oil then is ready to be passed into the first of a plurality ofneutralizing tanks 15 and 16 through a pipe 17, which tanks are filledto a predetermined depth with brucite, or equivalent material, through aremovable top, or manholes (not shown), or in any well known manner.

Each of the tanks 15 and 16 is provided with a frusto-conical bottomholding a screen 18, a discharge pipe 19 for neutralized oil, anoverflow pipe 20 for salts in solution, an upper fine mesh screen 21 ofmetal or cloth for holding the fines, an air pipe 22 for dislodging thefines from screen 21, and a steam or water pipe 23 below the lowerscreen 18.

The brucite is first crushed in lumps which may be one-half inch, moreor less, in diameter, and, after being placed in the tanks, is moistenedwith water or steam introduced through pipe 23. The acid oil is nowpassed through pipe 17 into the lower part of tank 15 (tank 16 being cutout of the system) and percolates upwardly through the interstices ofthe brucite, thereby coming into an intimate and extended contacttherewith.

The percolation results in the acid and acid reaction products beingbrought into contact with the contents of tank 15, whereby a more andmore intimate contact of the acid particles with the brucite willfollow. Likewise, in the subsequent washing the uppermost smallestparticles will go into solution more readily and can be carried out ofthe tank without clogging the same.

Upon exhaustion of the reactive effects of the brucite in tank 15, whichmay be determined by the condition of samples taken from the try cook34, valves 25 and 26 will be closed and valves 27 and 28 will be opened,whereby a continuous on-strcam flow of the acid distillate may bemaintained through tank 16.

Valve 29 in discharge pipe 20 of tank 15 is now opened and hot water orsteam and water is passed into tank 15 through pipe 23, whereby thesulphates, sulphonic, or other acid compounds, and any tarry or gummycompounds adsorbed on the surface of the brucite are dissolved orremoved therefrom, the velocity of the water flow being regulated toremove such of the particles of the brucite as are too fine foreflicient percolation. At the same time a blast of air, water, or steamthrough pipe 22 will free the screen 21 from any fines for their removalby the water stream.

The fiow of Water is continued until a completely new reactive surfaceof the brucite is prepared for further use, when the brucite in tank 16becomes exhausted, to maintain continuous operation. Steam, or air, maythen be blown in at pipe 20 to remove excess water through pipe 23.

It is, of course, apparent that any number of tanks 15 may be employedand various equivalent neutralizing materials as well, but the generalcondition is that the material should be insoluble in water and formsoluble salts upon reaction with acid compounds.

The system may be operated under superatmospheric temperatures andpressures, or a combina'tion thereof. This is desirable in theneutralization of acidtreated' lubricating oils, etc., where theviscosity of the cold stock interferes with efiicient percolation.

The process is applicable to oils having an acid reaction and in thisrespect is not limited to the neutralization of mineral oils containinginorganic acids, such as sulphuric or hydrochloric acids, or the like,but is effective for the neutralization of organic acids, such assulphonic acids, lwdrochlorides, or the like, as well as the free fattyacids, or organic acids, from vegetable or animal oils, the magnesium,or other reaction compounds, being removable by hot water, steam, orother suitable solvent.

Relatively small quantities of water are necessary to eflectively carryout the reaction by moistening the brucite, or other equivalentmaterial, and this use may be due to the necessity of ionizing theacids.

The water of crystallization formed by the reaction products is normallysumcient to remove this water from the finished product, but at timesthe neutralized product passing through line 19 may be filtered throughclay, fullers earth, diatomaceous earth, or the like, to completelyclarify and remove any traces of moisture in the treated oil.

The brucite, or other equivalent material, may be used to exhaustion andthis is often desirable to be done, or substantially so, before tanks 15and 16 are replenished.

The process herein described indicates a true chemical reaction whereinwater solublesalts of acids are formed and must not be confused withknown processes in which the contacting of acid oil with inert materialallegedly causes the agglomeration of acid. particles by surface tensioneflects. This distinction is best illustrated by the fact that anyparticular body of neutralizing material used in my process continuallydecreases in volume after each contact period and subsequent washingwhereas the passage of acid oil through bodies of chemically inertmaterials, such as sand, leaves the volume of such material unchanged.In the magnesium compounds used, the solubilities of which, in water atfrom 15 C. to 25 C., are less than 1, magnesium sulphates are formedhaving a solubility in water at the same temperatures in excess of 25,whereas sand, for instance, is unreactive with sulphuric acid or itsreaction products. It is, of course, obvious that the water necessaryfor moistening the material may be carried in the oil itself.

I claim as my invention:

1. A process of neutralization which comprises: contacting acidhydrocarbon oil with a, mineral containing MgO and moistened by aqueousfluid whereby soluble acid reaction products are formed, and removingsuch products by washing the mineral with water.

2. A process of neutralization which comprises: contacting acidhydrocarbon oil with a mineral containing MgO and moistened by aqueousfluid whereby water soluble acid reaction products are formed, andremoving such products by washing the mineral with water.

3. A process of neutralization which comprises: passing a stream of acidhydrocarbon oil through a body of contact material containing MgO and anaqueous solution of magnesium hydroxide, and holding reaction productsin aqueous solution while separating the hydrocarbons therefrom.

4. A process of neutralization which comprises: passing a stream of acidhydrocarbon oil through a body of contact material containing MgO and anaqueous solution of magnesium hydroxide, and holding reaction productsin aqueous solution within said body while separating the hydrocarbonstherefrom. I

5. A process of neutralization which comprises: passing a stream ofaqueous fluid and a stream of acid hydrocarbon liquids in successionthrough bodies of material containing magnesium oxide.

6. In a process of neutralization the combination of steps whichcomprise: passing a stream of aqueous fluid and a stream of acidhydrocarbon liquids in succession through a body of material containingmagnesium oxide.

7. A process of neutralization which comprises: contacting desludgedacid hydrocarbon liquids with suilicient aqueous solution containingmagnesium hydroxide in the presence of contact material to intimatelymix said liquids and solution, and separating the hydrocarbons from saidsolution while both are in fluid form; the entire process beingconducted at a substantially uniform temperature.

8. A process of neutralization which comprises: passing a stream ofhydrocarbon liquids containing sulphuric acid, through a body of contactmaterial containing MgO and coated with an aqueous solution containingmagnesium hydroxide and magnesium sulphate, and separating thehydrocarbons from the solution without substantial increase oftemperature in the solution while both are in fluid form.

9. A process of neutralization which comprises: passing a stream ofhydrocarbon liquids containing sulphuric acid, through a body of contactmaterial containing MgO and coated with an aqueous solution containingmagnesium hydroxide and magnesium sulphate at superatmospherictemperature, and separating the hydrocarbons from the solution withoutsubstantial increase of temperature in the solution while both are influid form.

10. A process of neutralization which comprises: passing a stream ofhydrocarbon liquids containing sulphuric acid, through a body of contactmaterial containing MgO and coated with an aqueous solution containingmagnesium hydroxide and magnesium sulphate at superatmospherictemperature and superatmospheric pressure, and separating thehydrocarbons from the solution without substantial increase .oftemperature in the solution while both are in fluid form.

11. A process of neutralization which comprises: interminglinglnrdrocarbon liquids contalning acid with an aqueous solution ofmagnesium hydroxide, increasing the concentration of magnesium hydroxidein said solution by the addition thereto of a magnesium salt of saidacid, and separating the hydrocarbons from said solution withoutsubstantial increase of temperature in said solution while both are influid form.

12. A process of neutralization which comprises: interminglinghydrocarbon oil containing acid with an aqueous solution of magnesiumhydroxide, increasing the concentration of magnesium hydroxide in saidsolution by the addition thereto of a magnesium salt of said acidderived from said hydrocarbons, and separating the hydrocarbons fromsaid solution without substantial increase of temperature in saidsolution while both are in fluid form.

13. A process of neutralization which comprises: contacting desludgedacid liquid hydrocarbons with suilicient aqueous solution of magnesiumhydroxide to neutralize said acid in the presence of contact material tointimately mix said liquids and solution, and separating thehydrocarbons from reaction products of neutralization while saidproducts are maintained in aqueous solution.

14. A process of neutralization which comprises: contacting liquidhydrocarbons containing acid with a mineral containing not less than 40%mo in the presence of suflicient water to maintain a solution of ma iumacid reaction 1'7. A process of neutralization which comprises: passinga stream of aqueous fluid and a stream of acid hydrocarbon liquids insuccession through a body of brucite.

18. A process of neutralization which comprises: passing a stream ofaqueous fluid and a stream of acid hydrocarbon liquids in successionthrough bodies of brucite.

19. A process of neutralization which comprises: passing a stream ofaqueous fluid and a stream of hydrocarbon liquids containing sulphuricacid in successionthrough a body of brucite.

LYLE CALDWELL.

